By Piya Sinha-Roy PARK CITY, Utah, Jan 20 (Reuters) - After a remarkable run with leading roles in films such as "The Dark Knight Rises" and "Inception," actor Joseph Gordon-Levitt stepped behind the camera to direct "Don Jon's Addiction," a raunchy comedy that premiered at the Sundance Film Festival. "Don Jon's Addiction," which Gordon-Levitt also wrote and stars in, leads a slate of films about sex on this year's Sundance roster.